Skeleton Yarn and Denim Fabric

ABSTRACT

Disclosed is skeleton yarn, comprising core-ply stretch yarn positioned at the center, middle-ply fine fiber or fine yarn spun made of fiber coating the surface of the core-ply stretch yarn, and outer-ply coarse fiber or coarse yarn spun made of fiber coating the surface of the middle-ply fine fiber or fine yarn spun made of fiber, wherein the middle-ply fine fiber or fine yarn spun made of fiber is high twist fiber, and the outer-ply coarse fiber or coarse yarn spun made of fiber is loose twist fiber. A novel retro denim fabric made from the skeleton yarn can be subjected to a normal post-finishing shrinking process, and the problems of unstable garment model and the like caused by unstable washing shrinkage can be avoided.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of Chinese Patent Application No. 201820370220.7 filed on Mar. 19, 2018, the contents of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to yarn and a fabric, particularly relates to skeleton yarn and a denim fabric, and belongs to the technical field of denim spinning.

BACKGROUND ART

The earliest denim uses indigo-dyed warp yarn and all-cotton non-elastic cotton yarn as weft. The coarse yarn has rough texture and is wear-resistant, durable and washable, and the cloth cover is coarse and has concave-convex creases. After continuous improvement, the denim with elasticity, soft hand feeling and different ingredients has entered thousands of households and even led the trend. However, in recent years, the retro style has arisen, and retro denim fabrics have appeared in response to consumer demands. Nowadays, the following problems exist for making the denim with the retro style:

(1) Nowadays, consumers have become accustomed to soft, comfortable and elastic fabrics, and the texture of the earliest coarse denim is unacceptable to the consumers.

(2) The retro stretch denim on the market has low elasticity, as it is difficult to enable the cloth cover to have coarseness and concave-convex creases due to the use of high-elasticity yarn.

(3) In order to form the retro denim fabric style, the warp-direction washing shrinkage of the fabric is expanded by post-treatment, so that when the ready-to-wear garment is washed with water, the shrinkage of the garment is increased to ensure that the cloth cover of the garment has an uneven retro style. However, this method is prone to size instability and difficulty in control in garment tailoring, resulting in the defects of different sizes and high defective rate.

Therefore, the prior art needs to be improved and developed.

SUMMARY OF THE INVENTION

Aiming at the problems existing in the prior art, the present invention is directed to skeleton yarn to overcome the defects of low elasticity, poor skin feeling and unstable size of the existing retro denim fabric.

Skeleton yarn is one kind of core spun yarn whose middle-ply is made of stiff spun yarn of high strength and twist and can act as support; skeleton yarn is made of by spining the middle-py with the core-ply stretch yarn and the coarse yarn spun made of fiber, therefore it looks in great shape and feels soft, that is called skeleton yarn.

The technical scheme of the present invention is as follows:

The skeleton yarn comprises core-ply stretch yarn positioned at the center, middle-ply fine fiber or fine yarn spun made of fiber coating the surface of the core-ply stretch yarn, and outer-ply coarse fiber or coarse yarn spun made of fiber coating the surface of the middle-ply fine fiber or fine yarn spun made of fiber.

Preferably, the middle-ply fine fiber or fine yarn spun made of fiber can be high twist fiber, and the outer-ply coarse fiber or coarse yarn spun made of fiber can be loose twist fiber.

A spinning mode of the skeleton yarn can be as follows: firstly, spinning the middle-ply fine fiber or fine yarn spun made of fiber with a twist which is 5-15% higher than the normal spinning twist, and spinning the obtained product with the core-ply stretch yarn by adopting a loose twist spinning process; and then, coating the outer-ply coarse fiber or coarse yarn spun made of fiber on the middle-ply fine fiber or fine yarn spun made of fiber and the core-ply stretch yarn by adopting the loose twist spinning process.

Preferably, the spinning mode of the skeleton yarn can be as follows: firstly, spinning the middle-ply fine fiber or fine yarn spun made of fiber with a twist which is 10% higher than the normal spinning twist, and spinning the obtained product with the core-ply stretch yarn by adopting a spinning process with a twist of 25-90T/10 cm; and then, coating the outer-ply coarse fiber or coarse yarn spun made of fiber on the middle-ply fine fiber or fine yarn spun made of fiber and the core-ply stretch yarn by adopting the spinning process with the twist of 25-90T/10 cm.

Preferably, the spinning mode of the skeleton yarn can be as follows: firstly, spinning the middle-ply fine fiber or fine yarn spun made of fiber with a twist which is 10% higher than the normal spinning twist, and spinning the obtained product with the core-ply stretch yarn by adopting a spinning process with a minimum twist of about 35T/10 cm.

A spinning mode of the skeleton yarn can be as follows: the outer-ply coarse fiber or coarse yarn spun made of fiber coats the middle-ply fine fiber or fine yarn spun made of fiber and simultaneously twists and coats the core-ply stretch yarn, wherein the outer-ply coarse fiber or coarse yarn spun made of fiber is twisted and coated by a loose twist method, and the middle-ply fine fiber is twisted and coated by a high twist method.

Preferably, the spinning mode of the skeleton yarn can be as follows: the outer-ply coarse fiber or coarse yarn spun made of fiber is twisted and coated with a twist of 25-90T/10 cm, and the middle-ply fine fiber is twisted and coated with a twist which is 5-15% higher than the normal spinning twist.

Preferably, the yarn count of the skeleton yarn can be 5S-50S, the yarn count scope of the middle-ply fine fiber or fine yarn spun made of fiber can be 10S-60S, and the yarn count scope of the core-ply stretch yarn can be 20D-450D.

Preferably, the yarn count of the skeleton yarn can be 6S-40S.

Preferably, the outer-ply coarse fiber or coarse yarn spun made of fiber can use short fiber with a fiber length of 8 mm-48 mm.

Preferably, the outer-ply coarse fiber or coarse yarn spun made of fiber can be fiber with a cooling, quick drying or heat preservation function.

Preferably, the outer-ply coarse fiber or coarse yarn spun made of fiber can be cotton yarn, Tencel fiber, Modal fiber, viscose fiber, polyester cotton blended yarn, Tencel cotton blended yarn or Modal cotton blended yarn.

Preferably, the middle-ply fine fiber or fine yarn spun made of fiber can use short fiber.

Preferably, the middle-ply fine fiber or fine yarn spun made of fiber can use cotton, cotton-containing blended yarn, non-cotton, non-cotton blended yarn or blended yarn of two or more kinds of fiber.

Preferably, the middle-ply fine fiber or fine yarn spun made of fiber can use cotton yarn, polyester cotton blended yarn, Tencel cotton blended yarn or Modal cotton blended yarn.

Preferably, the middle-ply fine fiber or fine yarn spun made of fiber can be OE yarn.

Preferably, the twist coefficient of the middle-ply fine fiber or fine yarn spun made of fiber can be 3.0-6.0.

The present invention is also directed to a denim fabric containing the above skeleton yarn.

The weft yarn of the denim fabric can use the above skeleton yarn.

The denim fabric can use a 3/1 twill, 2/1 twill or 1/1 plain weave structure.

The present invention has the following beneficial effects: the skeleton yarn of the present invention has a three-layer structure, wherein the middle-ply fine fiber or fine yarn spun made of fiber is spun by adopting a high twist spinning process so as to play a role of stiffening in the fabric; the outer-ply coarse fiber or coarse yarn spun made of fiber is spun by adopting a loose twist spinning process so as to play roles of softening, fluffing and improving hand feeling in the fabric; and the core-ply stretch yarn positioned at the center plays a role of shrinking in the fabric. The denim fabric adopting the skeleton yarn of the present invention has the following advantages: 1, the cloth cover has a good concave-convex effect and has a good retro style; 2, the denim fabric can be easily washed with water to realize a water washing effect and has multiple changes; 3, the denim fabric is good in elastic elongation and comfortable in hand feeling; and 4, the denim fabric is stable in washing shrinkage, small in radial washing shrinkage and stable in garment model. The final garment not only has rough and concave-convex corrugated styles of the retro denim but also has soft and close-fitting styles of the modern denim, and is comfortable to wear.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of skeleton yarn of the present invention.

FIG. 2 is a schematic diagram showing that middle-ply fine fiber or fine yarn spun made of fiber coats core-ply stretch yarn in an example 1 of the present invention.

FIG. 3 is a schematic diagram showing that outer-ply coarse fiber or coarse yarn spun made of fiber coats the middle-ply fine fiber or fine yarn spun made of fiber in the example 1 of the present invention.

FIG. 4 is a schematic diagram showing that the outer-ply coarse fiber or coarse yarn spun made of fiber and the middle-ply fine fiber or fine yarn spun made of fiber simultaneously coat the core-ply stretch yarn in an example 2 of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In order to make the objectives, technical schemes and effects of the present invention more clear and specific, the present invention is further described in detail by the following examples. It should be understood that the specific examples described herein are only used for explaining the present invention but are not intended to limit the present invention.

The skeleton yarn provided by the present invention comprises core-ply stretch yarn positioned at the center, middle-ply fine fiber or fine yarn spun made of fiber coating the surface of the core-ply stretch yarn, and outer-ply coarse fiber or coarse yarn spun made of fiber coating the surface of the middle-ply fine fiber or fine yarn spun made of fiber, wherein the middle-ply fine fiber or fine yarn spun made of fiber is high twist fiber, and the outer-ply coarse fiber or coarse yarn spun made of fiber is loose twist fiber.

Further, the outer-ply coarse yarn, the middle-ply and the inner layer are together spun into the skeleton yarn, and the overall count of the skeleton yarn is 6S-40S. Experiments prove that when the overall count of the skeleton yarn is expanded to 5S-50S, the effects of the skeleton yarn can also be realized. The yarn count scope of the middle-ply fine fiber or fine yarn spun made of fiber is preferably 10S-60S. If the middle-ply fine fiber or fine yarn spun made of fiber is too thin, the middle-ply fine fiber or fine yarn spun made of fiber is easy to break and cannot reflect a skeleton effect; and if the middle-ply fine fiber or fine yarn spun made of fiber is too thick, the weaving cannot be realized and the effect is bad. The yarn count scope of the core-ply stretch yarn is 20D-450D.

Further, the outer-ply coarse fiber or coarse yarn spun made of fiber only can be made from short fiber with a fiber length of 8 mm-48 mm. The short fiber has strong velvet feeling, and the fabric can obtain better shrinkage, so that a desired cloth cover effect can be achieved. The outer-ply coarse fiber or coarse yarn spun made of fiber can adopt fiber with a cooling, quick drying or heat preservation function, so that the fabric can have the cooling, quick drying or heat preservation function. The outer-ply coarse fiber or coarse yarn spun made of fiber can adopt cotton, cotton-containing blended yarn, non-cotton, non-cotton blended yarn or blended yarn of two or more kinds of fiber, and preferably adopt cotton yarn, Tencel fiber, Modal fiber, viscose fiber, polyester cotton blended yarn, Tencel cotton blended yarn, Modal cotton blended yarn, or the like. If the cotton yarn is adopted, the air permeability is good; if the polyester cotton blended yarn is adopted, the tenacity is high; and if the Tencel cotton blended yarn and the Modal cotton blended yarn are adopted, the hand feeling is better.

The raw material of the middle-ply fine fiber or fine yarn spun made of fiber can be made form short fiber or long fiber, wherein as the short fiber has better tenacity, the raw material made from the short fiber has the best effect. The middle-ply is made into fine yarn by adopting one or more kinds of blend fiber through a spinning process, the fine yarn has certain tenacity and twist and provides the tenacity of the overall skeleton yarn, and the yarn is spun at a certain twist, so that the overall yarn has convex feeling and is stiff. The middle-ply fine fiber or fine yarn spun made of fiber can adopt cotton, cotton-containing blended yarn, non-cotton, non-cotton blended yarn or blended yarn of two or more kinds of fiber, and preferably adopt cotton yarn, polyester cotton blended yarn, Tencel cotton blended yarn, Modal cotton blended yarn, or the like. If the cotton yarn is adopted, the air permeability is good; if the polyester cotton blended yarn is adopted, the tenacity is high; and if the Tencel cotton blended yarn and the Modal cotton blended yarn are adopted, the hand feeling is better. The spinning mode of the middle-ply fine fiber or fine yarn spun made of fiber can adopt air spinning, ring spinning, Siro spinning or compact spinning. Preferably, the spinning mode of the middle-ply fine fiber or fine yarn spun made of fiber is air spinning (namely OE yarn). The air spinning has the advantages that the yarn spun by air spinning has a smaller yarn count scope than ring spinning, is relatively fluffy and has relatively disordered arrangement, so that the yarn is stiffer in hand feeling.

Further, the middle-ply fine fiber or fine yarn spun made of fiber is high twist fiber with a twist which is about 10% higher than the normal spinning twist. As the middle-ply fiber has a higher twist, the fiber in the yarn has compact cohesion, the yarn has high tenacity, and a stiffening effect can be achieved.

Experiments prove that if the twist of the middle-ply fine fiber or fine yarn spun made of fiber is 5-15% higher than the normal spinning twist, the middle-ply fine fiber or fine yarn spun made of fiber also can achieve the stiffening effect. The twist of the middle-ply fiber can also be expressed by the twist coefficient and is 5-15% higher than the normal spinning twist, and the twist coefficient scope of the middle-ply fiber can be 3.0-6.0. The specific conversion formula is as follows:

Twist coefficient=(Twist/Inch)/√{square root over (English count)}

The spinning twist is affected by factors such as the material of the yarn and the size of the yarn count. The yarn with the same material and different yarn counts has different spinning twists and different twist coefficients of final products. For example, the normal twist of 32 pieces of cotton yarn is generally 90T/10 cm, and when the middle-ply fine fiber or fine yarn spun made of fiber adopts 32 pieces of cotton yarn, the twist is 10% higher than the normal spinning twist, i.e. the spinning twist is 99T/10 cm, and the twist coefficient is 4.4; the normal twist of 21S pieces of cotton yarn is 73T/10 cm, and when the middle-ply fine fiber or fine yarn spun made of fiber adopts 21 pieces of cotton yarn, the twist is 10% higher than the normal spinning twist, i.e. the spinning twist is 80T/10 cm, and the twist coefficient is 4.4; the normal twist of 32 pieces of Modal cotton blended yarn is 88T/10 cm, and when the middle-ply fine fiber or fine yarn spun made of fiber adopts 32 pieces of Modal cotton blended yarn, the twist is 10% higher than the normal spinning twist, i.e. the spinning twist is 99T/10 cm, and the twist coefficient is 4.4; and the normal twist of 20S pieces of pure Tencel OE yarn is 46T/10 cm, and when the middle-ply fine fiber or fine yarn spun made of fiber adopts 20S pieces of pure Tencel OE yarn, the twist is 15% higher than the normal spinning twist, i.e. the spinning twist is 52.9T/10 cm, and the twist coefficient is 3.0.

The outer-ply coarse fiber or coarse yarn spun made of fiber is loose twist fiber. Generally, when the outer-ply coarse yarn is coarse yarn, the twist is very small, and finally, the outer-ply coarse yarn, the middle-ply fine yarn and the inner-layer stretch yarn are spun by adopting a Siro spinning method. The outer-ply coarse fiber or coarse yarn spun made of fiber is spun by adopting a loose twist spinning process so as to play roles of softening, fluffing and improving hand feeling in the fabric.

Two spinning modes of the skeleton yarn are provided. The first spinning mode comprises the following steps: firstly, spinning the middle-ply fine fiber or fine yarn spun made of fiber with a twist being 10% higher than the normal spinning twist, and spinning the obtained product with the core-ply stretch yarn by adopting a spinning process with a minimum twist of about 35T/10 cm, wherein the also spinning process can be realized with the twist of 25-90T/10 cm, and the twist can be adjusted with the raw material and thickness of the yarn in the actual operation process; and then, coating the outer-ply coarse fiber or coarse yarn spun made of fiber on the middle-ply fine fiber or fine yarn spun made of fiber and the core-ply stretch yarn by adopting a loose twist spinning process with the twist of 25-90T/10 cm. The second spinning mode is as follows: the outer-ply coarse fiber or coarse yarn spun made of fiber coats the middle-ply fine fiber or fine yarn spun made of fiber and simultaneously twists and coats the core-ply stretch yarn, wherein the outer-ply coarse fiber or coarse yarn spun made of fiber is twisted and coated by a loose twist method with a twist of 25-90T/10 cm, and the middle-ply fine fiber is twisted and coated by a high twist method with a twist which is 5-15% higher than the normal spinning twist. In actual operation, the second mode is relatively simple and convenient to operate and is easy to control.

Further, the specific processes of the second spinning mode are as follows: an outer-ply fiber material is subjected to opening, combing, drawing and roving processes sequentially to prepare coarse yarn; a middle-ply fiber material is subjected to opening, combing, drawing, roving and fine spinning processes sequentially to prepare fine yarn; the inner-layer stretch yarn is fed into a front roller by a yarn guiding device with an embedded spinning technology, wherein the draft multiple of the stretch yarn is 1.5-4.0; the middle-ply fine yarn and the outer-ply coarse yarn pass through a bell mouth, a back roller, a middle roller and the front roller sequentially; when passing through the front roller, the middle-ply fine yarn is firstly wrapped with the inner-layer stretch yarn at the jaw of the front roller and then twisted and polymerized together with the outer-ply coarse yarn at the jaw of the front roller to form yarn, wherein the twist scope is 25-90T/10 cm; and finally, the skeleton yarn of which the yarn count scope is 5S-50S is obtained. During final spinning, a smaller twist is adopted, so that the surface of the yarn is fluffier, and the yarn is stiff and comfortable in touch.

Due to the characteristics of soft outside and stiff inside of the yarn, the inner-layer yarn with a high twist can ensure that the yarn has certain tenacity, can be used as warp yarn and weft yarn and is not limited to be used as weft yarn only because of low tenacity of general loose twist yarn. When the yarn is used as warp yarn in the denim fabric, the yarn needs to be dyed. Main dyes include indigo dyes, sulfur dyes and reactive dyes. However, the indigo dyes and the sulfur dyes are reducing dyes. Due to the problems of water insolubility and coloring of the dyes, only when the indigo dyes and the sulfur dyes are reduced to leuco compounds, the coloring effect is achieved by three processes of infiltration, diffusion and fixation. As the outer-ply yarn of the skeleton yarn is fluffier, the probability of contact between the fiber on the yarn and dye molecules is increased. During dyeing, the dye molecules are easily infiltrated, diffused and fixed on the fluffier yarn, thereby effectively solving the quality problems of color difference and the like during yarn dyeing, reducing the use of the dyes and chemicals to some extent, and simultaneously meeting the requirements of the dyeing effect. The dyed yarn is starched. As the yarn has a structure with a loose outer-ply and a tight inner layer, in the starching process, the slurry is easier to enter the looser fiber layer of the outer-ply, the inner-layer yarn has a higher twist, the fiber in the yarn has compact cohesion, and the yarn has high tenacity. Furthermore, by starching the yarn, wools on the surface of the yarn can be fit, so that on the premise of ensuring certain tenacity of the yarn, the starching rate can be effectively reduced, and the production cost can be lowered. In conclusion, the present invention also provides a denim fabric, and the weft yarn or warp yarn of the denim fabric adopts the skeleton yarn. The denim fabric can adopt a 3/1 twill, 2/1 twill or 1/1 plain weave structure.

EXAMPLE 1

Aiming at the problems existing in the existing retro denim fabric and the problem that the retro style fabric with concave-convex creases only can be made from stiffer yarn, and simultaneously considering the requirements for hand feeling and elasticity in modern times, the present invention provides a three-layer yarn structure with a loose outside and a stiff inside. Specifically, as shown in FIG. 1, the yarn comprises core-ply stretch yarn 1 (spandex in this example) positioned at the center, middle-ply fine fiber or fine yarn spun made of fiber 2 coating the surface of the core-ply stretch yarn, and outer-ply coarse fiber or coarse yarn spun made of fiber 3 coating the surface of the middle-ply fine fiber or fine yarn spun made of fiber, wherein the middle-ply fine fiber or fine yarn spun made of fiber 2 is high twist fiber with a twist being 10% higher than the twist of normal fiber, and the outer-ply coarse fiber or coarse yarn spun made of fiber 3 is loose twist fiber with a twist being 10% lower than the twist of normal fiber. The outer-ply of the whole skeleton yarn is fluffy, the middle-ply of the whole skeleton yarn is stiff and compact, and the innermost layer of the whole skeleton yarn coats the stretch yarn. When the fabric made from the skeleton yarn is washed with water, during shrinkage of the stretch yarn wrapped the sandwich layer, the stiff middle-ply does not shrink, and the fluffy outer-ply generates creases with the shrinkage of the stretch yarn. Therefore, a made novel retro denim fabric can be subjected to a normal post-finishing shrinking process, and the problems of unstable garment model and the like caused by unstable washing shrinkage can be avoided.

As shown in FIGS. 2-3, in this example, the spinning mode of the skeleton yarn is as follows: firstly, spinning the middle-ply fine fiber or fine yarn spun made of fiber 2 with a twist being 10% higher than the normal spinning twist, and spinning the obtained product with the stretch yarn 1 (spandex in this example) by adopting a spinning process with a minimum twist of about 35T/10 cm (as shown in FIG. 2); and then, coating the outer-ply coarse fiber or coarse yarn spun made of fiber 3 on the middle-ply fine fiber or fine yarn spun made of fiber 2 and the core-ply stretch yarn 1 (spandex) by adopting a loose twist spinning process with a twist being 10% lower than the normal spinning twist (as shown in FIG. 3), thereby finally obtaining the skeleton yarn of which the overall yarn count is 32S. In this example, the middle-ply fine fiber or fine yarn spun made of fiber 2 is OE yarn, and the outer-ply coarse fiber or coarse yarn spun made of fiber 3 is cotton.

This example also provides a denim fabric QAT01. The skeleton yarn is used as weft yarn, common denim yarn is used as warp yarn, and a 1/1 plain weave structure is adopted to make the denim fabric QAT01. In order to prove the beneficial effects of the present invention, another denim fabric QAT02 is made from the common yarn with the same specification by the same method for comparison, and the performance indexes of the denim fabric QAT01 and the denim fabric QAT02 are as shown in table 1:

TABLE 1 Performance indexes of denim fabric QAT01 and denim fabric QAT02 Data of novel retro product with three layers of yarn Warp- Weft- direction direction washing washing Elastic Variety name shrinkage shrinkage elongation QAT01  −3% −13% 26.8% QAT02 −13% −16%   12%

EXAMPLE 2

This example provides skeleton yarn, and the difference between the skeleton yarn of this example and the skeleton yarn of the example 1 is that the spinning mode of the skeleton yarn is as follows: as shown in FIG. 4, the outer-ply coarse fiber or coarse yarn spun made of fiber 3 coats the middle-ply fine fiber or fine yarn spun made of fiber 2 and simultaneously twists and coats the core-ply stretch yarn 1, wherein the outer-ply coarse fiber or coarse yarn spun made of fiber 3 is twisted and coated by a loose twist method, and the middle-ply fine fiber 2 is twisted and coated by a high twist method. The performance indexes of the denim fabric made from the skeleton yarn of this example are not significantly different from the performance indexes of the denim fabric made from the skeleton yarn of the example 1.

EXAMPLE 3

The skeleton yarn is characterized in that the core-ply stretch yarn adopts 40D spandex; the middle-ply fine fiber or fine yarn spun made of fiber adopts 40S polyester cotton blended yarn, and the twist coefficient is TM=4.2; the outer-ply coarse fiber or coarse yarn spun made of fiber adopts Modal yarn; and the outer-ply coarse fiber twists and coats the surface of the middle-ply fine fiber or fine yarn spun made of fiber by a loose twist method so as to be twisted and spun to finally obtain 10S skeleton yarn, and the measured yarn twist is 66T/10 CM.

The skeleton yarn is used as weft yarn, 10S pure cotton yarn is used as warp yarn, and a 3/1 right twill weave structure is adopted to weave a fabric product of this example. Common pure cotton yarn is used as weft yarn, and other ingredients, the same as those of the fabric product of this example, are adopted to weave a common fabric product. The warp-direction washing shrinkage, weft-direction washing shrinkage, elastic washing shrinkage, weft-direction tearing strength and weft-direction tensile strength of the two fabrics are tested, and the test data is as shown in table 2.

TABLE 2 Weft- Weft- Warp- Weft- direction direction direction direction tearing tensile washing washing Elastic Variety strength strength shrinkage shrinkage elongation name (N) (N) (%) (%) (%) Example 32 450 −2%  −8% 45% product Common 23 320 −8% −15% 28% product

EXAMPLE 4

The skeleton yarn is characterized in that the core-ply stretch yarn adopts 20D spandex; the middle-ply fine fiber or fine yarn spun made of fiber adopts 40S cotton yarn, and the twist coefficient is TM=4.0; the outer-ply coarse fiber or coarse yarn spun made of fiber adopts Modal yarn; and the outer-ply coarse fiber or coarse yarn spun made of fiber twists and coats the surface of the middle-ply fine fiber or fine yarn spun made of fiber by a loose twist method so as to be twisted and spun to finally obtain 9S skeleton yarn, and the measured yarn twist is 60T/10 CM.

The skeleton yarn is used as weft yarn, 12S pure cotton yarn is used as warp yarn, and a 3/1 left twill weave structure is adopted to weave a fabric product of this example. Common pure cotton yarn is used as weft yarn, and other ingredients, the same as those of the fabric product of this example, are adopted to weave a common fabric product. The warp-direction washing shrinkage, weft-direction washing shrinkage, elastic washing shrinkage, weft-direction tearing strength and weft-direction tensile strength of the two fabrics are tested, and the test data is as shown in table 3.

TABLE 3 Weft- Weft- Warp- Weft- direction direction direction direction tearing tensile washing washing Elastic Variety strength strength shrinkage shrinkage elongation name (N) (N) (%) (%) (%) Example 40 480 −1%  −5% 36% product Common 22 300 −8% −12% 21% product

EXAMPLE 5

The skeleton yarn is characterized in that the core-ply stretch yarn adopts 70D spandex; the middle-ply fine fiber or fine yarn spun made of fiber adopts 20S cotton yarn, and the twist coefficient is TM=4.7; the outer-ply coarse fiber or coarse yarn spun made of fiber adopts cotton yarn; and the outer-ply coarse fiber or coarse yarn spun made of fiber twists and coats the surface of the middle-ply fine fiber or fine yarn spun made of fiber by a loose twist method so as to be twisted and spun to finally obtain 6S skeleton yarn, and the measured yarn twist is 53T/10 CM.

The skeleton yarn is used as weft yarn, 8S Tencel cotton blended yarn is used as warp yarn, and a 3/1 right twill weave structure is adopted to weave a fabric product of this example. Common pure cotton yarn is used as weft yarn, and other ingredients, the same as those of the fabric product of this example, are adopted to weave a common fabric product. The warp-direction washing shrinkage, weft-direction washing shrinkage, elastic washing shrinkage, weft-direction tearing strength and weft-direction tensile strength of the two fabrics are tested, and the test data is as shown in table 4.

TABLE 4 Weft- Weft- Warp- Weft- direction direction direction direction tearing tensile washing washing Elastic Variety strength strength shrinkage shrinkage elongation name (N) (N) (%) (%) (%) Example 48 580  −2% −10% 68% product Common 30 350 −12% −21% 45% product

EXAMPLE 6

The skeleton yarn is characterized in that the core-ply stretch yarn adopts 80D spandex; the middle-ply fine fiber or fine yarn spun made of fiber adopts 16S Tencel cotton blended yarn, and the twist coefficient is TM=5.2; the outer-ply coarse fiber or coarse yarn spun made of fiber adopts Tencel fiber; and the outer-ply coarse fiber or coarse yarn spun made of fiber twists and coats the surface of the middle-ply fine fiber or fine yarn spun made of fiber by a loose twist method so as to be twisted and spun to finally obtain 8S skeleton yarn, and the measured yarn twist is 55T/10 CM.

The skeleton yarn is used as weft yarn, 9S pure cotton yarn is used as warp yarn, and a 3/1 right twill weave structure is adopted to weave a fabric product of this example. Common pure cotton yarn is used as weft yarn, and other ingredients, the same as those of the fabric product of this example, are adopted to weave a common fabric product. The warp-direction washing shrinkage, weft-direction washing shrinkage, elastic washing shrinkage, warp-direction tearing strength and warp-direction tensile strength of the two fabrics are tested, and the test data is as shown in table 5.

TABLE 5 Weft- Weft- Warp- Weft- direction direction direction direction tearing tensile washing washing Elastic Variety strength strength shrinkage shrinkage elongation name (N) (N) (%) (%) (%) Example 46 500  −3% −10% 62% product Common 31 340 −16% −20% 46% product

EXAMPLE 7

The skeleton yarn is characterized in that the core-ply stretch yarn adopts 140D spandex; the middle-ply fine fiber or fine yarn spun made of fiber adopts 14S Modal cotton blended yarn, and the twist coefficient is TM=5.0; the outer-ply coarse fiber or coarse yarn spun made of fiber adopts polyester cotton blended yarn; and the outer-ply coarse fiber or coarse yarn spun made of fiber twists and coats the surface of the middle-ply fine fiber or fine yarn spun made of fiber by a loose twist method so as to be twisted and spun to finally obtain 7S skeleton yarn, and the measured yarn twist is 51T/10 CM.

The skeleton yarn is used as weft yarn, 6S pure cotton yarn is used as warp yarn, and a 3/1 left twill weave structure is adopted to weave a fabric product of this example. Common pure cotton yarn is used as weft yarn, and other ingredients, the same as those of the fabric product of this example, are adopted to weave a common fabric product. The warp-direction washing shrinkage, weft-direction washing shrinkage, elastic washing shrinkage, warp-direction tearing strength and warp-direction tensile strength of the two fabrics are tested, and the test data is as shown in table 6.

TABLE 6 Weft- Weft- Warp- Weft- direction direction direction direction tearing tensile washing washing Elastic Variety strength strength shrinkage shrinkage elongation name (N) (N) (%) (%) (%) Example 43 550 −2% −12% 86% product Common 30 360 −7% −23% 60% product

EXAMPLE 8

The skeleton yarn is characterized in that the core-ply stretch yarn adopts 30D spandex; the middle-ply fine fiber or fine yarn spun made of fiber adopts 50S viscose fiber, and the twist coefficient is TM=5.4; the outer-ply coarse fiber or coarse yarn spun made of fiber adopts Modal cotton blended yarn; and the outer-ply coarse fiber or coarse yarn spun made of fiber twists and coats the surface of the middle-ply fine fiber or fine yarn spun made of fiber by a loose twist method so as to be twisted and spun to finally obtain 14S skeleton yarn, and the measured yarn twist is 75T/10 cM.

The skeleton yarn is used as weft yarn, 15S pure cotton yarn is used as warp yarn, and a 3/1 left twill weave structure is adopted to weave a fabric product of this example. Common pure cotton yarn is used as weft yarn, and other ingredients, the same as those of the fabric product of this example, are adopted to weave a common fabric product. The warp-direction washing shrinkage, weft-direction washing shrinkage, elastic washing shrinkage, warp-direction tearing strength and warp-direction tensile strength of the two fabrics are tested, and the test data is as shown in table 7.

TABLE 7 Weft- Weft- Warp- Weft- direction direction direction direction tearing tensile washing washing Elastic Variety strength strength shrinkage shrinkage elongation name (N) (N) (%) (%) (%) Example 38 380  −2% −10% 46% product Common 22 180 −13% −19% 25% product

EXAMPLE 9

The skeleton yarn is characterized in that the core-ply stretch yarn adopts 40D spandex; the middle-ply fine fiber or fine yarn spun made of fiber adopts air-spun 40S cotton yarn, and the twist coefficient is TM=4.8; the outer-ply coarse fiber or coarse yarn spun made of fiber adopts Modal yarn; and the outer-ply coarse fiber or coarse yarn spun made of fiber twists and coats the surface of the middle-ply fine fiber or fine yarn spun made of fiber by a loose twist method so as to be twisted and spun to finally obtain 12S skeleton yarn, and the measured yarn twist is 73T/10 CM.

The skeleton yarn is used as weft yarn, 7S pure cotton yarn is used as warp yarn, and a 3/1 left twill weave structure is adopted to weave a fabric product of this example. Common pure cotton yarn is used as weft yarn, and other ingredients, the same as those of the fabric product of this example, are adopted to weave a common fabric product. The warp-direction washing shrinkage, weft-direction washing shrinkage, elastic washing shrinkage, warp-direction tearing strength and warp-direction tensile strength of the two fabrics are tested, and the test data is as shown in table 8.

TABLE 8 Weft- Weft- Warp- Weft- direction direction direction direction tearing tensile washing washing Elastic Variety strength strength shrinkage shrinkage elongation name (N) (N) (%) (%) (%) Example 47 490 −1%  −6% 45% product Common 26 320 −9% −18% 35% product

EXAMPLE 10

The skeleton yarn is characterized in that the core-ply stretch yarn adopts 104D spandex; the middle-ply fine fiber or fine yarn spun made of fiber adopts air-spun 20S polyester cotton blended yarn, and the twist coefficient is TM=4.5; the outer-ply coarse fiber or coarse yarn spun made of fiber adopts Modal yarn; and the outer-ply coarse fiber or coarse yarn spun made of fiber twists and coats the surface of the middle-ply fine fiber or fine yarn spun made of fiber by a loose twist method so as to be twisted and spun to finally obtain 11S skeleton yarn, and the measured yarn twist is 68T/10 CM.

The skeleton yarn is used as weft yarn, 6S pure cotton yarn is used as warp yarn, and a 3/1 left twill weave structure is adopted to weave a fabric product of this example. Common pure cotton yarn is used as weft yarn, and other ingredients, the same as those of the fabric product of this example, are adopted to weave a common fabric product. The warp-direction washing shrinkage, weft-direction washing shrinkage, elastic washing shrinkage, warp-direction tearing strength and warp-direction tensile strength of the two fabrics are tested, and the test data is as shown in table 9.

TABLE 9 Weft- Weft- Warp- Weft- direction direction direction direction tearing tensile washing washing Elastic Variety strength strength shrinkage shrinkage elongation name (N) (N) (%) (%) (%) Example 50 530  −2% −12% 72% product Common 30 330 −14% −26% 60% product

EXAMPLE 11

The skeleton yarn is characterized in that the core-ply stretch yarn adopts 20D spandex; the middle-ply fine fiber or fine yarn spun made of fiber adopts air-spun 50S yarn, and the twist coefficient is TM=6.0; the outer-ply coarse fiber or coarse yarn spun made of fiber is blended by cotton, Tencel and polyester fiber; and the outer-ply coarse fiber or coarse yarn spun made of fiber twists and coats the surface of the middle-ply fine fiber or fine yarn spun made of fiber by a loose twist method so as to be twisted and spun to finally obtain 20S skeleton yarn, and the measured yarn twist is 82T/10 CM.

The skeleton yarn is used as weft yarn, 14S pure cotton yarn is used as warp yarn, and a 3/1 left twill weave structure is adopted to weave a fabric product of this example. Common pure cotton yarn is used as weft yarn, and other ingredients, the same as those of the fabric product of this example, are adopted to weave a common fabric product. The warp-direction washing shrinkage, weft-direction washing shrinkage, elastic washing shrinkage, warp-direction tearing strength and warp-direction tensile strength of the two fabrics are tested, and the test data is as shown in table 10.

TABLE 10 Weft- Weft- Warp- Weft- direction direction direction direction tearing tensile washing washing Elastic Variety strength strength shrinkage shrinkage elongation name (N) (N) (%) (%) (%) Example 30 436  −3%  −6% 80% product Common 15 250 −10% −20% 60% product

It should be understood that the application of the present invention is not limited to the above examples. For example, the outer-ply coarse fiber or coarse yarn spun made of fiber can also selected made of fiber with cooling, quick drying and heat preservation functions, and can also be selected from one or a combination of several kinds of Tencel fiber, Modal fiber and viscose fiber except the cotton mentioned in the above examples. The weave structure of the denim fabric can adopt a 3/1 twill weave structure, a 2/1 twill weave structure, and the like. Common technicians in this field can perform improvements or modifications with the above descriptions, and all improvements or modifications are intended to be included within the protection scope of the appended claims of the present invention. 

1. A skeleton yarn, comprising: core-ply stretch yarn positioned at the center, middle-ply fine fiber or fine yarn spun made of fiber coating the surface of the core-ply stretch yarn, and outer-ply coarse fiber or coarse yarn spun made of fiber coating the surface of the middle-ply fine fiber or fine yarn spun made of fiber.
 2. The skeleton yarn according to claim 1, wherein the middle-ply fine fiber or fine yarn spun made of fiber is high twist fiber, and the outer-ply coarse fiber or coarse yarn spun made of fiber is loose twist fiber.
 3. The skeleton yarn according to claim 1, wherein the spinning mode of the skeleton yarn is as follows: firstly, spinning the middle-ply fine fiber or fine yarn spun made of fiber with a twist being 5-15% higher than the normal spinning twist, and spinning the obtained product with the core-ply stretch yarn by adopting a loose twist spinning process; and then, coating the outer-ply coarse fiber or coarse yarn spun made of fiber on the middle-ply fine fiber or fine yarn spun made of fiber and the core-ply stretch yarn by adopting the loose twist spinning process.
 4. The skeleton yarn according to claim 1, wherein the spinning mode of the skeleton yarn is as follows: firstly, spinning the middle-ply fine fiber or fine yarn spun made of fiber with a twist being 10% higher than the normal spinning twist, and spinning the obtained product with the core-ply stretch yarn by adopting a spinning process with a twist of 25-90T/10 cm; and then, coating the outer-ply coarse fiber or coarse yarn spun made of fiber on the middle-ply fine fiber or fine yarn spun made of fiber and the core-ply stretch yarn by adopting the spinning process with the twist of 25-90T/10 cm.
 5. The skeleton yarn according to claim 4, wherein the spinning mode of the skeleton yarn is as follows: firstly, spinning the middle-ply fine fiber or fine yarn spun made of fiber with a twist being 10% higher than the normal spinning twist, and spinning the obtained product with the core-ply stretch yarn by adopting a spinning process with a minimum twist of about 35T/10 cm.
 6. The skeleton yarn according to claim 1, wherein the spinning mode of the skeleton yarn is as follows: the outer-ply coarse fiber or coarse yarn spun made of fiber coats the middle-ply fine fiber or fine yarn spun made of fiber and simultaneously twists and coats the core-ply stretch yarn, wherein the outer-ply coarse fiber or coarse yarn spun made of fiber is twisted and coated by a loose twist method, and the middle-ply fine fiber is twisted and coated by a high twist method.
 7. The skeleton yarn according to claim 6, wherein the spinning mode of the skeleton yarn is as follows: the outer-ply coarse fiber or coarse yarn spun made of fiber is twisted and coated with a twist of 25-90T/10 cm, and the middle-ply fine fiber is twisted and coated with a twist being 5-15% higher than the normal spinning twist.
 8. The skeleton yarn according to claim 1, wherein the yarn count of the skeleton yarn is 5S-50S, the yarn count scope of the middle-ply fine fiber or fine yarn spun made of fiber is 10S-60S, and the yarn count scope of the core-ply stretch yarn is 20D-450D.
 9. The skeleton yarn according to claim 1, wherein the yarn count of the skeleton yarn is 6S-40S.
 10. The skeleton yarn according to claim 1, wherein the outer-ply coarse fiber or coarse yarn spun made of fiber uses short fiber with a fiber length of 8 mm-48 mm.
 11. The skeleton yarn according to claim 1, wherein the outer-ply coarse fiber or coarse yarn spun made of fiber is fiber with a cooling, quick drying or heat preservation function.
 12. The skeleton yarn according to claim 1, wherein the outer-ply coarse fiber or coarse yarn spun made of fiber is cotton yarn, Tencel fiber, Modal fiber, viscose fiber, polyester cotton blended yarn, Tencel cotton blended yarn or Modal cotton blended yarn.
 13. The skeleton yarn according to claim 1, wherein the middle-ply fine fiber or fine yarn spun made of fiber uses short fiber.
 14. The skeleton yarn according to claim 1, wherein the middle-ply fine fiber or fine yarn spun made of fiber uses cotton, cotton-containing blended yarn, non-cotton, non-cotton blended yarn or blended yarn of two or more kinds of fiber.
 15. The skeleton yarn according to claim 1, wherein the middle-ply fine fiber or fine yarn spun made of fiber uses cotton yarn, polyester cotton blended yarn, Tencel cotton blended yarn or Modal cotton blended yarn.
 16. The skeleton yarn according to claim 1, wherein the middle-ply fine fiber or fine yarn spun made of fiber is OE yarn.
 17. The skeleton yarn according to claim 1, wherein the twist coefficient of the middle-ply fine fiber or fine yarn spun made of fiber is 3.0-6.0.
 18. A denim fabric containing the skeleton yarn according to claim
 1. 19. A denim fabric, wherein the weft yarn of the denim fabric uses the skeleton yarn according to claim
 1. 20. The denim fabric according to claim 19, using a 3/1 twill, 2/1 twill or 1/1 plain weave structure. 